Each of the PLSS had two columns of horizontal Velcro strips on the back.  Ken Thomas, a member of Hamilton Sundstrand's Space Hardware Heritage Team and author of U.S. Spacesuits (2006, Springer-Praxis), writes "The white cover - or Thermal Meteoroid Garment -  on the PLSS was designed and fabricated by Hamilton Standard (now Hamilton Sundstrand), Windsor Locks, CT.  In zero gravity, if an astronaut wished to look out the Lunar Module windows, he would have difficulty keeping position.  Where his feet would be was the rack where the CDR PLSS and both OPSs were stored. In zero-G simulations, someone damaged an antennae on an OPS mounted in the rack of the simulator."

"Because the astronauts were already wearing booties with Velcro hook on the bottoms, patches of Velcro pile could be placed on the back of the CDR PLSS and the tops of the OPSs to provide a crew member with places to anchor his feet so he would not floating around and potentially damaging things while he was doing visual positioning or recreational star gazing.  Once the Velcro was there, additional uses for sample bags and tool pouches were found as the missions evolved."  The LMP's PLSS was stowed on the cabin floor next to the hatch.  These also had Velcro strips, perhaps in the interest of interchangability.